Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 8 Jul 2026 15:52:20 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org, Andres Freund <andres@anarazel.de>
Subject: Re: Add per-backend AIO statistics
Message-ID: <ak3zpA2HHh5CxQK8@paquier.xyz>
References: <akzcq9jtWK5C92g1@bdtpg>
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On Tue, Jul 07, 2026 at 11:02:03AM +0000, Bertrand Drouvot wrote:
> 1/ pg_aios that lists all AIO handles that are currently in use. That sho=
ws
> what's happening right now, but not what has happened.
>=20
> 2/ pg_stat_get_backend_io() that shows how much IO was done, but not how =
it
> was done. There's no way to see whether IOs ran synchronously or
> asynchronously, whether a backend was stalling on handle exhaustion, or h=
ow
> completions are distributed across backends.

While the information may be useful, one thing that sounds very
important to me is how this impacts workloads by default.

Andres is usually able to catch bottlenecks that everybody else is
unable to see, so perhaps checking with him the location of these
extra function calls would be a good first step.  Your proposal goes
down to pgaio_io_stage(), pgaio_io_process_completion() and
pgaio_submit_staged() to track these counter increments.
--
Michael

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